In a curiously sudden announcement, both Ucchy-san of Rockman Unity and Capcom Retro Games announced over Twitter that Rockman 5: Blues' Trap!? will be available on PSN in Japan today, starting this evening. There was no prior announcement to the game being released, as far as I can recall. Hopefully this makes its way over to the west as well, although we've still yet to see a release of Rockman 4 on the PS1 Imports. This of course is the enhanced PS1 version, andlike the other PSN releases ought to run for ¥600.
With both PSN and the Wii VC up to Rockman 5, I suppose the race is on to see which service gets Rockman 6: The Greatest Battle in History!! first.